Shuyi Zhang

Nanjing University, Nan-ching, Jiangsu Sheng, China

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Publications (10)14.08 Total impact

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    ABSTRACT: In this work, lanthanide doped zinc oxide nanoparticles synthesized in room-temperature ionic liquid via a sonochemical method have been studied. Firstly, the cavitation bubble temperatures in 1-butyl-3-methylimidazolium hexafluorophosphate (ImPF6) have been estimated by the methyl radical recombination method. The temperatures measured in ImPF6 are in the range of 3000–4000 K. Secondly, a facile method has been proposed to prepare lanthanide (III) doped zinc oxide nanoparticles in ImPF6 via an ultrasonic irradiation. The nanomaterials are studied by transmission electron microscopy, X-ray diffraction, photoacoustic and luminescence techniques. The results show that the relaxation processes of the samples depend strongly on the lanthanide doping. Moreover, a mechanism is proposed to interpret the formation of lanthanide (III) doped zinc oxide nanoparticles in the ImPF6 upon ultrasonic irradiation.
    Science China: Physics, Mechanics and Astronomy 07/2013; 56(7). · 1.17 Impact Factor
  • Dan Wu, Chao Tao, Xiaojun Liu, Shuyi Zhang
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    ABSTRACT: In photoacoustic tomography, a scanning setup or an array of transducers is usually needed to record the photoacoustic signal on a closed trajectory surrounding the region of interest. Such a measurement configuration may increase the complexity or expense of the photoacoustic tomography system. In this study, a one-channel photoacoustic tomography using time reversal invariance of photoacoustics in a chaotic cavity is proposed. In no need of the scanning setup or transducer array, the method utilizes only one fixed small-size transducer to collect the photoacoustics in the cavity. The method is verified by two-dimensional numerical simulations. Moreover, the influence of noise and the diameter of the transducer are also taken into account to verify the robustness and practicality of the proposed method. The proposed method could be helpful for improving the image quality of photoacoustic tomography using a few data channels.
    International Journal of Thermophysics 10/2012; · 0.57 Impact Factor
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    ABSTRACT: The sonochemical process has been proved to be a useful technique for generating various nanostructured materials. The physical and chemical effects of cavitation are highly dependent on the contents of the collapsing bubble and hence on the choice of solvent. Recently, room-temperature ionic liquid (RTIL) have been developed to a central point of interest in both academia and industry. RTIL are nonvolatile, non-flammable, and thermally stable solvents. These properties make ionic liquids potentially attractive for use in sonochemical reactions. The application of ultrasound to synthesis nanomaterials in conjunction with ionic liquids, however, has been rarely exploited. In this work, a facile approach has been developed for the preparation of neodymium doped zinc oxide nanopaticles in RTIL via an ultrasonic irradiation. The morphology and properties of the products have been characterized by X-ray diffraction and transmission electron microscopy. A possible mechanism is proposed to explain the formation neodymium doped zinc oxide nanoparticles via ultrasonic irradiation.
    The Journal of the Acoustical Society of America 04/2012; 131(4):3228. · 1.65 Impact Factor
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    ABSTRACT: Nanocrystalline titania as photocatalyst has attracted considerable attention for its potential use in environmental cleaning. Recently, lanthanide ions doped titania samples have been shown to increase the photocatalytic efficiency of selected reactions. In this work, TiO2 nanoparticles doped with Er3+ were prepared via an ultrasonic assisted sol-gel method. The optical properties of the samples were determined by photoacoustic (PA) spectroscopy. It was found that the absorption edge shifted to lower wavelength when the particle size fell into nanometer range, which is the evidence of a quantum size effect. The nature of ligand bonding to Er3+ and the structural properties were investigated with the PA absorptions of the f-f transitions of Er3+, which are sensitive to the local environment. The results showed that TiO2 gel heated at 70 °C still contained abundant trapped water and ethanol, and the environment around Er3+ was similar to the one in the aqueous ion. The “degree of covalency” for Er3+ bonding increased continuously during the gel-to-anatase transition. For the sample calcined at 1100 °C, however, the f-f transitions of Er3+ showed blue shifts and the intensity of the hypersensitive transition decreased, indicating an increase of ionicity in the Er3+ bonding. This can be attributed to the segregation of Er3+ ions to the external surface, forming Er2Ti2O7 during the anatase-to-rutile transition, which was confirmed with XRD and TEM measurements.
    Journal of Rare Earths 04/2010; 28(2):211-214. · 1.36 Impact Factor
  • Yuetao Yang, Xiaojun Liu, Shuyi Zhang
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    ABSTRACT: Lanthanide complexes Ln(p-ABA)(3).H(2)O (p-ABA: p-aminobenzoic acid; Ln(3+):La(3+), Tb(3+) and Er(3+)) have been incorporated into silica gels via a sol-gel method. Upon heat treatment at 120 degrees C, photoacoustic (PA) intensity of the ligand increases for Tb(3+), La(3+) and Er(3+) complexes in silica gels, respectively, while this difference cannot be observed for the samples without heat treatment. Different PA intensities of the samples are interpreted by comparison with their luminescence spectra. The nephelauxetic parameters and PA branching vectors of Er(3+) complex in silica gel have been calculated. Spectral results indicate that p-ABA does not coordinate with lanthanide ions in silica matrix without a suitable heat treatment. For the co-doped samples, it is shown that the emissions of Tb(3+) are enhanced with addition of La(p-ABA)(3).H(2)O and remarkably quenched with the addition of Er(p-ABA)(3).H(2)O. The possible mechanisms for these phenomena are proposed.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 11/2009; 75(2):543-6. · 1.98 Impact Factor
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    ABSTRACT: The photophysical properties of lanthanide complexes have been studied extensively; however, fundamental parameters such as the intrinsic quantum yield as well as radiative and nonradiative decay rates are difficult or even impossible to measure experimentally. Herein, a photoacoustic (PA) method is proposed to determine the intrinsic quantum yield of lanthanide complexes with lifetimes in the order of milliseconds. This method is used to determine the intrinsic quantum yields for europium(III)-containing metallomesogens as well as terbium(III) complexes. The results show that the PA signal is sensitive to both the lifetime and the ratio of the fast-to-slow heat component of the samples. It is found that there is an efficient ligand sensitization and a moderate intrinsic quantum yield for the complexes. The intrinsic quantum yield of Eu(3+) in the metallomesogens exhibits an obvious increase upon the isotropic liquid to smectic A transition. The proposed PA method is quite simple, and can contribute to a clearer understanding of the photophysical processes in luminescent lanthanide complexes.
    ChemPhysChem 04/2008; 9(4):600-6. · 3.35 Impact Factor
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    ABSTRACT: Lanthanide-containing liquid crystals exhibiting smectic A phase close to room temperature were obtained. Photoacoustic (PA) spectroscopy was used to study the spectral properties and phase transitions of liquid crystalline metal complexes. It was found that PA intensity of the ligand had a relationship with the probability of nonradiative transitions, which increased in the order of Eu(tta)3L2 < La(tta)3L2< Tb(tta)3L2<Er(tta)3L2. The relaxation processes of the complexes were studied in depth from two aspects: radiative and non-radiative processes, combining with their fluorescence spectra. Phase transitions of europium(III) and erbium(III) complexes, in the temperature range of 383–358 K, could be clearly monitored by both PA amplitude and PA phase signals. As the temperature crossed the transition point, PA amplitude showed a minimum and PA phase a maximum. The results indicated that PA technique could serve as a new tool for investigating the physicochemical properties of liquid crystals containing metal ions.
    Journal of Rare Earths. 01/2008;
  • Yuetao Yang, Shuyi Zhang
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    ABSTRACT: The photoacoustic (PAS) spectra and luminescence spectra of Eu(Hba)3 Phen and coprecipitates Eu0.6Ln0.4(Hba)3 Phen complexes (Ln:Y, Nd; Hba: benzoic acid; Phen: phenanthroline) have been measured, and the co‐luminescence effect of the coprecipitates are reported. The PAS intensities of the central lanthanide ions are interpreted in terms of the probability of nonradiative transitions. It is found that the PAS intensity of the ligand bears a relationship with the energy transfer processes. The PAS intensity in the region of ligand absorption increases in the order of Eu0.6Nd0.4(Hba)3 Phen > Eu(Hba)3 Phen > Eu0.6Y0.4(Hba)3 Phen, which indicates that addition of the second lanthanide ions in each case changes the relaxation processes of the complexes. The energy transfer and relaxation processes are discussed in combination with the luminescence spectra.
    Spectroscopy Letters 08/2006; 37(1):1-10. · 0.67 Impact Factor
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    ABSTRACT: A photoacoustic piezoelectric method based on a simplified thermoelastic theory is employed to determine thermal diffusivities of biological tissues. The thermal diffusivities of porcine tissues with different preparation conditions, including fresh, dry and specially prepared conditions, are characterized. Comparing the experimental evaluated diffusivities of the tissues in three conditions with each other, it can be seen that the diffusivities of the fresh tissues are the biggest and the diffusivities of the specially prepared tissues are bigger than that of the dry ones generally. The results show that the piezoelectric photoacoustic method is especially effective for determining macro-effective (average) thermal diffusivities of biological materials with micro-inhomogeneity and easy to be performed, which can provide useful information for researching thermal characters of biological tissues. Keywordsthermo-elastic theory-photoacoustic effect-piezoelectric effect-biological tissues-thermal properties
    Chinese Science Bulletin 01/2004; 49(20):2115-2119. · 1.37 Impact Factor
  • Yuetao Yang, Shuyi Zhang
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    ABSTRACT: Neodymium complexes with amino acids: Nd(Ala)(3)Cl(3).3H(2)O, Nd(Val)(3)Cl(3).3H(2)O, Nd(Phe)Cl(3).5H(2)O and Nd(Trp)(3)Cl(3).3H(2)O (Ala: L-alanine, Val: L-valine, Phe: L-phenylalanine, Trp: L-tryptophan) are synthesized and their photoacoustic (PA) spectra are reported. The nephelauxetic ratio beta, bonding parameter b(1/2) and Sinha parameter delta are calculated based on their PA spectra. The variation of these parameters and correlation of them with the nature of metal-ligand bonding are discussed. The PA intensity analysis of the f-f transitions of neodymium ion is carried out by calculating the intensity branching vector. The environmental effect on the f-f transitions of neodymium ion is also studied. The branching vectors of the f-f transitions of Nd(Ala)(3)Cl(3).3H(2)O and Nd(Val)(3)Cl(3).3H(2)O are similar, which indicates the perturbation of the two ligand fields is similar. The branching vectors of energy levels 4G(5/2)+(2)G(7/2) of Nd(Phe)Cl(3).5H(2)O and Nd(Trp)(3)Cl(3).3H(2)O increase remarkably compared with those of Nd(Ala)(3)Cl(3).3H(2)O and Nd(Val)(3)Cl(3).3H(2)O. As the degree of covalency increases, the oscillator strength of the hypersensitive transition exhibits a corresponding increase. The relaxation process of Nd(Ala)(3)Cl(3).3H(2)O is established through its PA and electron absorption spectroscopy (EAS). A method used to resolve the PA amplitude spectrum is suggested. With the phase spectrum, PA absorption bands of Nd(Trp)(3)Cl(3).3H(2)O are resolved well in the region of ligand absorption.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 05/2003; 59(6):1205-12. · 1.98 Impact Factor